1. Field of the Invention
This invention relates to dishwashers and, in particular, to sealing structure between a rotary spray arm and a stationary pedestal supporting the spray arm.
2. Description of the Prior Art
Various structures have been used in the art to prevent leakage at the juncture between a rotary spray arm and a stationary pedestal for supporting the spray arm. While it is not absolutely critical that leakage be entirely prohibited, any leakage diminishes the pressure established in the spray arm, which delivers washing liquid to the wash chamber, and is therefore detrimental and should be minimized.
It is known to provide a gasket closely between cooperating spray arm and spray arm support structure to prevent the escape of the liquid therebetween. U.S. Pat. No. 3,642,207, to Krogman, discloses seal assemblies 100, 102 between rotating and stationary parts associated with a spray assembly. These seal assemblies are compressed between the rotating and stationary parts and thus are subject to substantial wear after prolonged use. When this occurs the seal is compromised. Additionally, the friction generated between the seal assemblies, rotating and stationary parts inhibits free rotation of the spray arm. Still further, the assembly of the seal assemblies in the Krogman structure is a relatively complicated process.
In U.S. Pat. No. 3,599,872, to Guth, a sealing tape is disclosed which fits relatively loosely in an annular space between cooperating parts on a rotary spray arm and a stationary support therefor. The ends of the tape overlap each other to define a ring, the diameter of which can be enlarged under the pressure of liquid delivered through a pump. As the pump operates the tape is progressively deformed radially outwardly from top to bottom to seal an opening between two vertically spaced, radially inwardly facing, sealing surfaces on the spray arm and stationary support. A substantial amount of pressure is required to effect deformation of the seal sufficiently to establish a seal with good integrity. Further, as the seal is conforming to the sealing surfaces, a substantial amount of leakage occurs.